1. Field of the Invention
The present invention relates to handheld dehiders and powered skinning knives used to remove the hide of a carcass in a meat processing facility. More specifically, the present invention relates to reducing the vibration of dehiders that use a pair of cutting disks driven in opposed cutting oscillations.
2. Description of Related Art
Handheld dehiders are used in processing facilities to remove the hide from an animal carcass. The most common type of dehider includes a pair of adjacent cutting disks or blades that are driven in opposed cutting oscillations by a corresponding pair of pushrods. The basic design is shown in U.S. Pat. No. 5,122,092 assigned to Jarvis Products Corporation, the assignee of the present invention. Similar dehider designs are shown and described in U.S. Pat. Nos. 4,368,560, 3,435,522 and 2,751,680.
In the dehider design described in the patents above, each cutting blade includes teeth around its perimeter. The adjacent disk blades are driven in opposed cutting oscillations by a pair of pushrods connected to an eccentric drive mechanism operated by a pneumatic motor mounted in the handle of the tool.
The motor rotates a pinion gear, which turns a main drive gear oriented at ninety degrees to the axis of the motor. The main drive gear turns the eccentric shaft to oscillate the pushrods. During each oscillation, the teeth on one disk blade move past the teeth on the adjacent and oppositely moving disk blade. This produces a shearing and cutting action that quickly removes the hide from the carcass.
Although this dehider design has proven effective, the oscillating nature of the eccentric-driven pushrods and blades results in substantial vibration. A known method of reducing this vibration is to use a counterbalance mass on the main drive gear, however, this solution is only partly effective. In order to avoid interference with the oscillating pushrods, the main drive gear and any counterbalance mass connected thereto must be vertically offset from the plane of the pushrods. The offset between the moving mass of the pushrods and the oppositely moving mass of the counterbalance on the main drive gear produces a wobbling motion.
Initially, the magnitude of this wobbling motion is quite limited and the tool can be used comfortably for long periods of time. However, over time, the wobbling motion produces significant excess wear. As the bearings and moving parts begin to wear, the wobble increases in amplitude until it produces an extremely objectionable vibration. Moreover, the wear produced by this motion shortens the lifetime of the component parts in the tool.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a handheld dehider with less vibration that can be comfortably used for long periods of time.
It is another object of the present invention to provide a handheld dehider that wears less rapidly due to reduced vibration.
A further object of the invention is to provide a counterbalanced eccentric shaft for a handheld dehider with an integrated counterbalance mass.
It is yet another object of the present invention to provide a counterbalance cup for a handheld dehider with an integrated counterbalance mass.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.